tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/SupportFunctions/arm_float_to_q15.c

   1 /* ----------------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_float_to_q15.c
   9 *
  10 * Description:  Converts the elements of the floating-point vector to Q15 vector.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * ---------------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupSupport
  45  */
  46
  47 /**
  48  * @addtogroup float_to_x
  49  * @{
  50  */
  51
  52 /**
  53  * @brief Converts the elements of the floating-point vector to Q15 vector.
  54  * @param[in]       *pSrc points to the floating-point input vector
  55  * @param[out]      *pDst points to the Q15 output vector
  56  * @param[in]       blockSize length of the input vector
  57  * @return none.
  58  *
  59  * \par Description:
  60  * \par
  61  * The equation used for the conversion process is:
  62  * <pre>
  63  *      pDst[n] = (q15_t)(pSrc[n] * 32768);   0 <= n < blockSize.
  64  * </pre>
  65  * \par Scaling and Overflow Behavior:
  66  * \par
  67  * The function uses saturating arithmetic.
  68  * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
  69  * \note
  70  * In order to apply rounding, the library should be rebuilt with the ROUNDING macro
  71  * defined in the preprocessor section of project options.
  72  *
  73  */
  74
  75
  76 void arm_float_to_q15(
  77   float32_t * pSrc,
  78   q15_t * pDst,
  79   uint32_t blockSize)
  80 {
  81   float32_t *pIn = pSrc;                         /* Src pointer */
  82   uint32_t blkCnt;                               /* loop counter */
  83
  84 #ifdef ARM_MATH_ROUNDING
  85
  86   float32_t in;
  87
  88 #endif /*      #ifdef ARM_MATH_ROUNDING        */
  89
  90 #ifndef ARM_MATH_CM0_FAMILY
  91
  92   /* Run the below code for Cortex-M4 and Cortex-M3 */
  93
  94   /*loop Unrolling */
  95   blkCnt = blockSize >> 2u;
  96
  97   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  98    ** a second loop below computes the remaining 1 to 3 samples. */
  99   while(blkCnt > 0u)
 100   {
 101
 102 #ifdef ARM_MATH_ROUNDING
 103     /* C = A * 32768 */
 104     /* convert from float to q15 and then store the results in the destination buffer */
 105     in = *pIn++;
 106     in = (in * 32768.0f);
 107     in += in > 0 ? 0.5 : -0.5;
 108     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
 109
 110     in = *pIn++;
 111     in = (in * 32768.0f);
 112     in += in > 0 ? 0.5 : -0.5;
 113     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
 114
 115     in = *pIn++;
 116     in = (in * 32768.0f);
 117     in += in > 0 ? 0.5 : -0.5;
 118     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
 119
 120     in = *pIn++;
 121     in = (in * 32768.0f);
 122     in += in > 0 ? 0.5 : -0.5;
 123     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
 124
 125 #else
 126
 127     /* C = A * 32768 */
 128     /* convert from float to q15 and then store the results in the destination buffer */
 129     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
 130     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
 131     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
 132     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
 133
 134 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 135
 136     /* Decrement the loop counter */
 137     blkCnt--;
 138   }
 139
 140   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 141    ** No loop unrolling is used. */
 142   blkCnt = blockSize % 0x4u;
 143
 144   while(blkCnt > 0u)
 145   {
 146
 147 #ifdef ARM_MATH_ROUNDING
 148     /* C = A * 32768 */
 149     /* convert from float to q15 and then store the results in the destination buffer */
 150     in = *pIn++;
 151     in = (in * 32768.0f);
 152     in += in > 0 ? 0.5 : -0.5;
 153     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
 154
 155 #else
 156
 157     /* C = A * 32768 */
 158     /* convert from float to q15 and then store the results in the destination buffer */
 159     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
 160
 161 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 162
 163     /* Decrement the loop counter */
 164     blkCnt--;
 165   }
 166
 167
 168 #else
 169
 170   /* Run the below code for Cortex-M0 */
 171
 172   /* Loop over blockSize number of values */
 173   blkCnt = blockSize;
 174
 175   while(blkCnt > 0u)
 176   {
 177
 178 #ifdef ARM_MATH_ROUNDING
 179     /* C = A * 32768 */
 180     /* convert from float to q15 and then store the results in the destination buffer */
 181     in = *pIn++;
 182     in = (in * 32768.0f);
 183     in += in > 0 ? 0.5f : -0.5f;
 184     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
 185
 186 #else
 187
 188     /* C = A * 32768 */
 189     /* convert from float to q15 and then store the results in the destination buffer */
 190     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
 191
 192 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 193
 194     /* Decrement the loop counter */
 195     blkCnt--;
 196   }
 197
 198 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 199
 200 }
 201
 202 /**
 203  * @} end of float_to_x group
 204  */